In reply to message posted by Gary H:
When the toilet is being used and when it is flushed, I hear water trickling noise from the bathtub. Is this a normal condition related to how/where both are being vented. I have what appear to be moth flies in this area and wondered if the noise and flies are related.
Hey Gary, if you see flies coming out of your drains this is a clasic sign of trap seal loss.
A trap seal can be lost 8 various ways BUT the most common is capillary action or partically blocked venting.
If these flies can get through your trap seal so can dangerious sewer gasses.
Try either snaking or water jetting these lines and see if it still is happening.
You should try the following.
Try filing your bathtub to the overflow and then let it out and listen for a gurgling sound.
Then fill your basin to the over flow rim and let it ot and see if any water backs up into your tub.
This is very basic to look for a possible restriction in the lines vent or waste